Nuclear magnetic resonance (NMR) techniques will be used to study molecular dynamics in liquid crystals and in membrane systems. Diffusion in oriented lecithin/water bilayers will be measured as a function of temperature and of lipid concentration. Diffusion in water/mixed lipid systems and in lipid bilayers containing cholesterol will also be investigated. Membrane phase transitions will be investigated using proton enhanced carbon-13 NMR. A spectrometer is being completed and the studies will focus on molecular configuration changes which accompany phase transitions in bilayers. NMR relaxation mechanisms in nematic liquid crystals will be studied using isotropic dilution techniques. By measuring proton relaxation in partially deuterated p-methoxy-benzylidine-p-n-butyl-aniline (MBBA) as a function of dilution in perdeuterated MBBA the inter- and intramolecular contributions to T1 can be determined. These contributions will be obtained as a function of frequency and temperature, then compared with theoretical predictions. BIBLIOGRAPHIC REFERENCES: "Frequency Dependence of Proton Relaxation in Liquid Crystals," B.M. Fung, C.G. Wade and R.D. Orwoll, Journal of Chemical Physics 64, 148 (1976). "Determination of the Lateral Diffusion Coefficient of Potassium Oleate in the Lamellar Phase," S.B.W. Roeder, E.E. Burnell, A.L. Kuo and C.G. Wade, Journal of Chemical Physics 64, 1848 (1976).